Modern research leading to the successful demonstration of encapsulation of tissue culture derived from plants has initiated a line of research focused on the development of synthetic or “manufactured” seeds. Manufactured seeds generally include encapsulated somatic or zygotic plant embryos that functionally mimic development of naturally propagated seeds. Such manufactured seeds may reduce labor costs and increase efficiency in many modern agriculture (including silviculture) applications. Examples of manufactured seeds are disclosed, for example, in U.S. Pat. No. 5,701,699, issued to Carlson et al., the disclosure of which is hereby expressly incorporated by reference.
Typical manufactured seeds include a seed shell, synthetic gametophyte, and a plant embryo. A manufactured seed that does not include the plant embryo is known in the art as a “seed blank.” The seed blank typically is a cylindrical capsule having a closed end and an open end. The synthetic gametophyte is placed within the seed shell to substantially fill the interior of the seed shell. A longitudinally extending hard porous insert, known as a shoot restraint, may be centrally located within one end of the seed shell, surrounded by the synthetic gametophyte, and includes a centrally located cavity extending partially through the length of the shoot restraint. The plant embryo is deposited within the cavity of the shoot restraint. The plant embryo is then sealed within the seed blank by an end seal, which may be coated with an antibiotic substance.
Although known manufactured seeds are generally effective in providing an inexpensive delivery unit for plant tissue culture, there are many opportunities to improve current seed design. For example, one problem with some manufactured seeds involves low numbers of successful germinants. Many factors can lead to germination failure; however, most manufactured seeds typically exhibit some form of abnormal growth that indicates germination may not be successful. Being able to identify abnormal growth patterns and provide seed design solutions could significantly help advance manufactured seed technology.
Thus, there is a need to continually improve the design of manufactured seeds to reduce abnormal growth of embryos. Improvements to manufactured seed design that lead to an increased number of successful and vigorous germinants (when compared with conventional manufactured seed designs) would be particularly desirable in this field of developing technology. Ideally, seed design improvements may also help improve cost and efficiency models for utilization of manufactured seed technology.